1. Area of the Art
The present invention relates to medical devices and to methods for the administration and withdrawal of fluids from a patient. Particularly, the present invention relates to catheter or cannula placement devices including those which are emplaced by passing the catheter through a hollowed needle.
2. Description of the Prior Art
Catheters effective for use within the context of various medical procedures are known, and generally formed from flexible materials to enable their placement in desired locations within patients. Likewise, conventional systems for placing catheters in any number of desired positions generally rely upon needles for ingress into desired vessels.
It has become generally known that insertion of catheters may be accomplished either by coaxially mounting a catheter onto a needle (over-the-needle) or by locating a catheter inside of the lumen of a needle (through-the-needle). Prior art devices of both of these types are subject to numerous pitfalls and constraints which significantly complicate the setting up of an intravenous fluid delivery system.
Prominent among the drawbacks with through-the-needle devices is removal of the needle which is required to place the devices into patients. With a catheter or cannula disposed inside, a cannula having its proximate end housed within a needle is inserted through the skin with the appropriate placement of its tip inside of the desired blood vessel. Withdrawal of the needle leaves the catheter or cannula properly within the vessel.
In order to withdraw apparatus involved in through-the-needle catheter placement, it is important to immediately remove the needle from the assembly to minimize trauma caused to the involved patients. Likewise, known systems require that needles be removed by retracting the same upwardly along the catheter, often causing further injury and trauma to patients. Further, the needles themselves are responsible for numerous cut cannulae or catheters and subsequent loss of the catheter within the body, and have motivated aspects of the teachings of the present invention.
With a catheter located inside of the lumen of the needle, withdrawal of the needle is of prime importance once proper placement has been achieved. It is difficult to remove needles so situated owing to the gross geometrical constraints from the hub at the proximate end of the catheter.
Splitting of needles was first practiced in U.S. Pat. Nos.:
______________________________________ 3,569,658; 3,382,872; 4,100,893; 4,306,652; 4,401,433; 4,449,973; 4,559,04; and 4,610,691. ______________________________________
However, each of these references disclosed rendering the needle splittable by forming the needle in two longitudinal halves, or by effecting longitudinal scoring of the same, and manipulating the entire mechanism in attempts to split the needles.
Additionally, the needles have induced damages to patients and to the intravenous assembly itself have limited the efficacy of these devices. Attempts to overcome these problems have ranged from different types of detachable needle-splitters to techniques for removing the needle assembly from the catheter once situated. Unfortunately, unwanted perforation and shearing of the external portions of catheters remains a major problem.
Prior art through-the-needle catheters and mechanisms have failed to adequately address these issues. For example, U.S. Pat. Nos. 4,957,488 and 4,957,489 which both issued to Cameron and Doman on Sep. 18, 1990 and are assigned to CRITIKON, INC., tried to arrest forward motion of a needle in combination with a rapidly deformable catheter cannula. The needle, however, continues to present difficulty on the basis of the its lack of facile extradition from the prior art devices.
Likewise, the present inventor has developed Percutaneous Port Assemblies (U.S. Pat. No. 5,569,217; issued Oct. 29, 1996), Hardened Tip over-the-needle catheters, as shown in U.S. Pat. No. 5,683,370; which issued Nov. 4, 1997 and Dual Lurnen catheters in U.S. Pat. No. 5,522,807 and 5,554,136; the latter of which was issued Sep. 10, 1996 and U.S. Pat. Nos.:
______________________________________ 4,377,165; 4,100,393; 4,254,081; 4,401,433; 4,559,043; 4,610,671; 4,612,170; 4,874,373; 4,950,252; 4,950,256; 4,964,854; 5,098,394; ______________________________________
each of which is patentably distinguishable from the teachings of the present invention.
Accordingly, although advances have been made in catheter introduction and placement technologies, clearly there exists a longstanding desire to innovate novel enhanced ways for permitting needles to be removed without concomitant damages to catheters and tissue. Although various attempts to accomplish the same have employed elaborate and circumlocuted means, it has now been discovered that significant aspects this problem can be eliminated.